double post but cannot remove it, pasting the solution here as well
world = unreal.get_editor_subsystem(unreal.UnrealEditorSubsystem).get_editor_world()
subLevelList = unreal.EditorLevelUtils.get_levels(world)
for subLevel in subLevelList:
subLevelPackageName = subLevel.get_package().get_name()
streamingLevel = unreal.GameplayStatics.get_streaming_level(world, subLevelPackageName)
if streamingLevel:
print (subLevel.get_path_name())
print (streamingLevel.is_level_visible())